The epidemiology of gonorrhoea, chlamydial infection and syphilis in four African cities.

OBJECTIVES: To compare the epidemiology of gonorrhoea, chlamydial infection and syphilis in four cities in sub-Saharan Africa; two with a high prevalence of HIV infection (Kisumu, Kenya and Ndola, Zambia), and two with a relatively low HIV prevalence (Cotonou, Benin and Yaoundé, Cameroon). DESIGN: Cross-sectional study, using standardized methods, including a standardized questionnaire and standardized laboratory tests, in four cities in sub-Saharan Africa. METHODS: In each city, a random sample of about 2000 adults aged 15-49 years was taken. Consenting men and women were interviewed about their socio-demographic characteristics and their sexual behaviour, and were tested for HIV, syphilis, herpes simplex virus type 2 (HSV-2), gonorrhoea, chlamydial infection, and (women only) Trichomonas vaginalis infection. Risk factor analyses were carried out for chlamydial infection and syphilis seroreactivity. RESULTS: The prevalence of gonorrhoea ranged between 0% in men in Kisumu and 2.7% in women in Yaoundé. Men and women in Yaoundé had the highest prevalence of chlamydial infection (5.9 and 9.4%, respectively). In the other cities, the prevalence of chlamydial infection ranged between 1.3% in women in Cotonou and 4.5% in women in Kisumu. In Ndola, the prevalence of syphilis seroreactivity was over 10% in both men and women; it was around 6% in Yaoundé, 3-4% in Kisumu, and 1-2% in Cotonou. Chlamydial infection was associated with rate of partner change for both men and women, and with young age for women. At the population level, the prevalence of chlamydial infection correlated well with reported rates of partner change. Positive syphilis serology was associated with rate of partner change and with HSV-2 infection. The latter association could be due to biological interaction between syphilis and HSV-2 or to residual confounding by sexual behaviour. At the population level, there was no correlation between prevalence of syphilis seroreactivity and reported rates of partner change. CONCLUSION: Differences in prevalence of chlamydial infection could be explained by differences in reported sexual behaviour, but the variations in prevalence of syphilis seroreactivity remained unexplained. More research is needed to better understand the epidemiology of sexually transmitted infections in Africa

Correlation between Associated Trees, Cocoa Trees and Carbon Stocks Potential in Cocoa Agroforests of Southern Cameroon

This study was conducted in the Cocoa Agro-Forests (CAF) of Mengomo’s locality. The aim was to evaluate the influence of some factors on carbon stocks. The sampling was done in 30 plots of 25 x 25 m 2 in which all trees with a dbh?10 cm were inventoried. The Shannon, Simpson and Evernnessindexes were calculated to characterize the diversity of trees associated with cocoa. 62 species belonging to 48 genera and 27 families were identified, the Anacardiaceae, Moraceae, Caesalpiniaceae,  Mimosaceae and Rutaceae, were revealed the most diverse families, with 5 species each. Shannon’s (3.66), Evernness’s (0.76) and Simpson’s (0.96) indexes have reflected a low diversity, dominated by some fewspecies. The average density of cocoa trees is 1028 trees/ha. They store about 22.51±5.86 Mg C/ha. Associated trees stored 124.20±60.05Mg C/ha for tree density of 113 trees/ha. These CAF sequestered about 146.71Mg C/ha. The multiple correspondence analyses showed that carbon stocks in the CAF are positively correlated with the associated trees and the age of the CAF and negatively correlated with the abundance of cocoa trees. The biomass of cocoa is independent of the associated trees, but is inversely related to the density of the associated trees

HIV Genetic Diversity in Cameroon: Possible Public Health Importance

To monitor the evolving molecular epidemiology and genetic diversity of HIV in a country where many distinct strains cocirculate, we performed genetic analyses on sequences from 75 HIV-1-infected Cameroonians: 74 were group M and 1 was group O. Of the group M sequences, 74 were classified into the following env gp41 subtypes or recombinant forms: CRF02 (n = 54), CRF09 (n = 2), CRF13 (n = 2), A (n = 5), CRF11 (n = 4), CRF06 (n = 1), G (n = 2), F2 (n = 2), and E (n = 1, CRF01), and 1 was a JG recombinant. Comparison of phylogenies for 70 matched gp41 and protease sequences showed inconsistent classifications for 18 (26%) strains. Our data show that recombination is rampant in Cameroon with recombinant viruses continuing to recombine, adding to the complexity of circulating HIV strains. This expanding genetic diversity raises public health concerns for the ability of diagnostic assays to detect these unique HIV mosaic variants and for the development of broadly effective HIV vaccines.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63150/1/aid.2006.22.812.pd

Role of CCL3L1-CCR5 Genotypes in the Epidemic Spread of HIV-1 and Evaluation of Vaccine Efficacy

Polymorphisms in CCR5, the major coreceptor for HIV, and CCL3L1, a potent CCR5 ligand and HIV-suppressive chemokine, are determinants of HIV-AIDS susceptibility. Here, we mathematically modeled the potential impact of these genetic factors on the epidemic spread of HIV, as well as on its prevention.Ro, the basic reproductive number, is a fundamental concept in explaining the emergence and persistence of epidemics. By modeling sexual transmission among HIV+/HIV- partner pairs, we find that Ro estimates, and concordantly, the temporal and spatial patterns of HIV outgrowth are highly dependent on the infecting partners' CCL3L1-CCR5 genotype. Ro was least and highest when the infected partner possessed protective and detrimental CCL3L1-CCR5 genotypes, respectively. The modeling data indicate that in populations such as Pygmies with a high CCL3L1 gene dose and protective CCR5 genotypes, the spread of HIV might be minimal. Additionally, Pc, the critical vaccination proportion, an estimate of the fraction of the population that must be vaccinated successfully to eradicate an epidemic was <1 only when the infected partner had a protective CCL3L1-CCR5 genotype. Since in practice Pc cannot be >1, to prevent epidemic spread, population groups defined by specific CCL3L1-CCR5 genotypes might require repeated vaccination, or as our models suggest, a vaccine with an efficacy of >70%. Further, failure to account for CCL3L1-CCR5-based genetic risk might confound estimates of vaccine efficacy. For example, in a modeled trial of 500 subjects, misallocation of CCL3L1-CCR5 genotype of only 25 (5%) subjects between placebo and vaccine arms results in a relative error of approximately 12% from the true vaccine efficacy.CCL3L1-CCR5 genotypes may impact on the dynamics of the HIV epidemic and, consequently, the observed heterogeneous global distribution of HIV infection. As Ro is lowest when the infecting partner has beneficial CCL3L1-CCR5 genotypes, we infer that therapeutic vaccines directed towards reducing the infectivity of the host may play a role in halting epidemic spread. Further, CCL3L1-CCR5 genotype may provide critical guidance for optimizing the design and evaluation of HIV-1 vaccine trials and prevention programs

Induced abortion among women attending antenatal clinics in Yaounde, Cameroon.

OBJECTIVES: Unsafe abortion is a public health concern because of its impact on maternal morbidity and mortality. The objective of this study was to document on induced abortion in Yaounde, Cameroon. DESIGN: Cross-sectional study. SETTING: Six antenatal clinics in Yaounde, Cameroon. METHODS: Women attending antenatal clinics between October and December 1998 were included in the study and interviewed. Nulliparous were women with no previous delivery and multiparous were defined as women who had at least one previous delivery. RESULTS: Out of the 1532 women, five hundred seventy-two were nulliparous and 960 were multiparous. Of the nulliparous women 17% reported a previous abortion ever; this proportion exceeded 35% in those over 24 years. For multiparous women, the proportion who reported an abortion (between the last birth and present pregnancy) was 22%. In multivariate analysis on the group of nulliparous women, older age, having used modern contraception and having spent more than two years in the city were significantly associated with induced abortion. In the multiparous group, older age, having a full time job and antenatal clinic were significantly associated with induced abortion. CONCLUSIONS: This study shows that induced abortion is a common practice in urban Cameroon. Because of restrictive laws, a substantial proportion of these abortions are likely to be unsafe, with the risk of associated complications. There is a need for expanded comprehensive sexual and reproductive health services